THE BIOLOGY OF THE CELL SURFACE 



conserving static Moment. On the other side, the living 

 thing is highly mobile, changing with every change in the 

 environment, accommodating itself and thus evincing 

 capacity for self-regulation. In the protoplasmic system 

 the ectoplasm is the region of active momentary changes in 

 response to environmental conditions.^ Within the proto- 

 plasmic system is a stability that is derived from the inter- 

 play of the more static and the more mobile factor. This 

 stability thus brought about determines both that organiza- 

 tion of matter called living thing and that specificity which 

 sets off one living thing from another. 



To the varying states of the protoplasm due to the con- 

 comitant and succeeding reactions we need especially to 

 address ourselves. The region of the protoplasmic system 

 in which these changes are most strongly revealed is the 

 ectoplasm. Its most important characteristic is its change 

 in time, its rapid response to outside conditions. No other 

 cell-component exhibits this characteristic in a like degree. 



By re-evaluating structure and function of the proto- 

 plasmic system, my theory of the ectoplasm has signifi- 

 cance not only for the advance of biological investigation; 

 it offers a point of view also for medicine — the highest 

 form of applied biology — whence medical problems can be 

 surveyed. 



Medicine, as human biology, a welter of complex rela- 

 tions, even less than the biology of other animals can depend 

 upon the ultimate particles of physical science for the 

 solution of its problems.^ As protoplasmic systems, human 

 cells are capable of study by comparable cytological tech- 

 nique and experimental methods which used on eggs have 

 furnished the particulars that give basis for my general- 

 ization. An insistent demand for medicine today is, 

 therefore, a far-flung attack on human cells as such. We 



^ Cf. Montgomery, igo4. 



~ See Sauerbruch, 1^26, 1937. 



